With the acceleration of globalization, the role of ports in urban economic growth is becoming increasingly prominent. However, its traditional operating methods have also caused significant pressure on the environment, leading to worsening air pollution problems. Public concern for health and the environment has made transforming ports a top priority. Despite these measures, air and health indicators in some port cities have not improved significantly, and health conditions in some cities have even deteriorated. In addition, many academic explorations research on port cities has focused on reducing energy consumption and greenhouse gases, without systematically studying the social and environmental risks of just transition in port cities. Therefore, this article uses data from 10 port cities from 2013 to 2022, combined with multiple regression and Kuznets curve for in-depth analysis. The research found that in areas with high population density, the relationship between port transformation and Air Quality Index(AQI) forms an inverted N-shaped curve, while in areas with low population density, it is an n-shaped curve. This reveals the non-linear impact of port transformation on air pollution. From a health perspective, the just transition of ports has always been beneficial for the health of urban residents, especially in areas with high population density. This means that the impact of the transformation of ports on the environment and on health depends not only on the depth of the transformation, but also on regional characteristics. This study focused on how the transition could improve air quality, and the study also delved into its long-term impact on the health of city residents. This provides valuable information for the development of sustainable strategies in port cities, helping them to more effectively improve their environmental and health conditions.